I am loading a data layer in a google map, over a certain country (it's a drawing over a country):
map.data.addGeoJson(geoJsonObject);
I am pretty sure there isn't, but... is there a way to check that the bounds of the map are inside the bounds of the data layer?
(basically, I want to know, when the user navigates on the map, if the current viewport is inside data layer);
var bounds = this.map.getBounds();
var sw = bounds.getSouthWest();
Maybe I can query the data layer in the position of the south west bound and check for some props. indicating that I am inside that data layer?
Or at least:
Does anyone know a way how to get a certain feature object programmatically, knowing the lat and long?
Here the google maps uses events to get to the feature object:
map.data.addListener('click', function(event) {
event.feature.setProperty('isColorful', true);
});
But I do not want to use events. Is there a method to supply the coordinates of a point and get to the feature object? Something like:
map.getFeature(lat, long).setProperty('isColorful', true);
google.maps.LatLngBounds.contains
function could be utilized for that purpose, but since it accepts a single location, the following solution is suggested:
1) initialize data layer bounds from GeoJSON coordinates:
var dataLayer = map.data;
var layerBounds = new google.maps.LatLngBounds();
//1.collect all coordinates from data layer
dataLayer.forEach(function(f) {
var geometry = f.getGeometry();
processCoordinates(geometry, layerBounds.extend, layerBounds);
});
2) determine whether map bounds are within a layer bounds:
if (layerBounds.contains(map.getBounds().getNorthEast()) && layerBounds.contains(map.getBounds().getSouthWest())) {
//...
}
Working example
In the provided example green colored area will be displayed if map bounds are within a layer bounds, and the red colored in the opposite case:
var area;
function initMap() {
var map = new google.maps.Map(document.getElementById('map'), {
center: {
lat: 53.349248,
lng: -6.255323
},
zoom: 6,
mapTypeId: google.maps.MapTypeId.TERRAIN
});
displayDataLayer(map);
document.getElementById("btnShow").onclick = function() {
var result = displayDataLayerBoundsArea(map);
};
}
function displayDataLayer(map) {
var dataLayer = map.data;
dataLayer.loadGeoJson('https://gist.githubusercontent.com/vgrem/440708612b574764c309/raw/2a4e2feadc204806440c51a14c2ef1f54f4fc3d8/Census2011_Province_generalised20m.json');
dataLayer.setMap(map);
}
function displayDataLayerBoundsArea(map) {
var dataLayer = map.data;
var layerBounds = new google.maps.LatLngBounds();
//1.collect all coordinates from data layer
dataLayer.forEach(function(f) {
var geometry = f.getGeometry();
processCoordinates(geometry, layerBounds.extend, layerBounds);
});
if (area != null) {
area.setMap(null);
}
//2.determine whether map bounds are contained within a layer bounds
if (layerBounds.contains(map.getBounds().getNorthEast()) && layerBounds.contains(map.getBounds().getSouthWest())) {
//map.fitBounds(bounds);
area = new google.maps.Rectangle({
strokeColor: '#00FF00',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#00FF00',
fillOpacity: 0.35,
map: map,
bounds: {
north: layerBounds.getNorthEast().lat(),
south: layerBounds.getSouthWest().lat(),
east: layerBounds.getNorthEast().lng(),
west: layerBounds.getSouthWest().lng()
}
});
} else {
//map.fitBounds(bounds);
area = new google.maps.Rectangle({
strokeColor: '#FF0000',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#FF0000',
fillOpacity: 0.35,
map: map,
bounds: {
north: layerBounds.getNorthEast().lat(),
south: layerBounds.getSouthWest().lat(),
east: layerBounds.getNorthEast().lng(),
west: layerBounds.getSouthWest().lng()
}
});
}
}
function processCoordinates(geometry, callback, thisArg) {
if (geometry instanceof google.maps.LatLng) {
callback.call(thisArg, geometry);
} else if (geometry instanceof google.maps.Data.Point) {
callback.call(thisArg, geometry.get());
} else {
geometry.getArray().forEach(function(g) {
processCoordinates(g, callback, thisArg);
});
}
}
#map {
width: 800px;
height: 640px;
}
<button id="btnShow">Show</button>
<div id="map"></div>
<script async defer src="https://maps.googleapis.com/maps/api/js?callback=initMap"></script>